FR-A-2 533 965, for example, already discloses a mechanism employing fluid under pressure, such as a hydraulic pump or motor, comprising: a stator; a rotor; a device for assembling the rotor with respect to the stator, such that these two elements rotate relatively about a geometrical axis and said two elements are maintained axially in position, in the two opposite directions parallel to said geometrical axis; a reaction cam fast with a first of said two elements; cylinders arranged in the second of these two elements and disposed substantially radially with respect to said geometrical axis of rotation; and pistons mounted to slide in said cylinders and bearing on said cam.
Constant research has been carried out with regard to these known mechanisms, motors or pumps, with a view to reducing their space requirement, both radial and axial. However, such research has been limited to a certain extent, as the designers, up to the present time, have had to provide at least two sets of bearings in order to ensure rotational assembly and axial holding of the rotor with respect to the stator. Such bearings are either mixed, each of them producing both part of the rotational assembly and part of the axial holding, or each being of one type, one of the bearings producing rotational assembly, and one or more other bearings effecting axial holding.
It is an object of the present invention to propose a novel bearing arrangement which considerably reduces the axial and radial space requirement of said mechanisms, whilst conserving at least the same endurance and having mechanical aptitudes (fatigue strength, recovery of moments) at least equal to those of the known mechanisms.